High Precision Hy-CI Variational Calculations for the Ground State of Neutral Helium and Helium-Like ions

Published

April 1, 2002

Author(s)

James S. Sims, Stanley A. Hagstrom

Abstract

Hylleraas-Configuration Interaction (Hy-CI) method variational calculations with up to 4648 expansion terms are reported for the ground ¹S state of neutral helium. Convergence arguments are presented to obtain estimates for the exact nonrelativistic energy of this state. The nonrelativistic energy is calculated to be -2.9037 2437 7034 1195 9829 99 a.u. Comparisons with other calculations and an energy extrapolation give an estimated nonrelativistic energy of -2.9037 2437 7034 1195 9830(2) a.u., which agrees well with the best previous variational energy, -2.9037 2437 7034 1195 9829 955 a.u., of Korobov (Phys Rev A 2000, 61, 64503), obtained using the universal (exponential) variational expansion method with complex exponents (Frolov, A.M.; Smith, V.H. Jr. J Phys B Atom Mol Opt Phys 1995, 28, L449). In addition to He, results are also included for the ground¹S states of H^-, Li⁺, Be⁺⁺, and B⁺³.

Citation

International Journal of Quantum Chemistry

Volume

90

Pub Type

Journals

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Keywords

B+3 ground state energy, Be++ ground state energy, CI-HY variational calculation high preci, H-ground state energy Li+ ground state e, helium ground state calculation, HY-CI variational calculation, Hylleraas-configuration interaction

Citation

Sims, J. and Hagstrom, S. (2002), High Precision Hy-CI Variational Calculations for the Ground State of Neutral Helium and Helium-Like ions, International Journal of Quantum Chemistry, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=150834 (Accessed December 13, 2024)